Journal of Pipeline Systems Engineering and Practice

The expansion of urban communities around the world resulted in the installation of utility pipes near existing natural or artificial slopes. These pipes can experience significant increase in axial earth pressure as a result of possible slope movement in the pipeline direction. This research aims at utilizing the discrete-element method to investigate the response of a buried pipeline in granular material subjected to axial soil movement. To determine the input parameters needed for the discrete-element analysis, calibration is performed using triaxial and direct shear test data and the microscopic parameters are determined by matching the numerical and experimental results. The soil–pipe system is then modeled and the detailed behavior of the pipe and the surrounding soil as well as their interaction at the particle-scale level are presented. Conclusions are made regarding the suitability of the empirical approach used in practice to estimate the axial soil resistance in different soil conditions. This study suggests that caution should be exercised in calculating axial soil resistance to relative pipe movement in dense sand material. A suitable lateral earth pressure coefficient should be determined in these cases as a function of the soil and pipe properties.

Deflection measurements and finite-element simulation were conducted for buried steel pipes that had been installed using a staged construction technique. The pipes were mortar lined, with a 2,743-mm (108-in.) internal diameter, and the backfill material consisted of controlled low-strength material (CLSM) and compacted native soil. The section analyzed in this paper was part of a 241-km (150-mi) Tarrant Regional Water District (TRWD) project that will be used to transfer water from a reservoir in Kennedale, Texas, to an outlet in Arlington, Texas. Three measurement techniques were adopted and compared for measuring the pipe deflection during the construction procedure: a published procedure, a photo laser profiler, and a video laser profiler. The behavior of the pipe tested was simulated with the finite-element analysis (FEA) method. Material tests, based on established standards, were conducted to develop an initial material law for the CLSM. Material, geometry, and contact nonlinearities were used to simulate the actual behavior of the system. A uniform thermal load was applied to simulate stress-induced compaction at every soil layer. Finally, the deflection, calculated with FEA, was compared with the results from the field measurements. From this study, it is concluded that the FEA successfully simulated the staged construction method. Moreover, the laser profiler is recommended rather than the published method because those results were significantly closer to the actual deflection.

A small-scale liquefaction process without any extra energy consumption was proposed to liquefy a part of natural gas in the pressure-reducing station. A heat exchanger network was integrated with two turboexpander-driven compressors to achieve higher performance of the natural gas liquefaction process in a pressure-reducing station. On the basis of the process simulation, the effects of the feed gas pressure ($p_1$) and the final and intermediate expansion pressures ($p_{10}$ and $p_7$) on system performance have been investigated to determine the optimal design conditions for the proposed system. The results showed that the liquefaction rate (LR) and the exergy utilization rate (EUR) can reach their maximal values of 17.8 and 28.2%, respectively, at the optimal condition, where $p_1=\mathrm{6,241}\mathrm{kPa}$, $p_7=\mathrm{5,000}\mathrm{kPa}$, and $p_{10}=\mathrm{1,600}\mathrm{kPa}$. The optimized LR and EUR have been increased by 41.2 and 43.8% compared with the corresponding values from the literature.

A penstock is a conduit which is normally used to convey water from a reservoir to hydraulic turbines. It is made by joining a number of pieces of pipe whose proper alignments are essential to minimize the flow disturbances and hydraulic losses. This paper experimentally investigates the effect of misalignment of two pipes of the same diameter on hydraulic losses at five different Reynolds numbers ranging from $5.34\times {10}^5$ to $6.22\times {10}^5$. The diametric misalignment between the two pieces of mild steel penstock of inner diameter 342 mm is varied from 2 to 10 mm in steps of 2 mm. There is a loss of pressure head at the location of mismatch of the diameters, which increases with increase in misalignment and Reynolds number.

This article presents a new approach for the computation of the water surface angle in pipes arranged in parallel. Estimating this parameter in partially filled pipes is an important task in the solution of many practical problems in the different branches of the engineering profession such as flow measurement and design of drainage networks, where the flow is mostly of the free surface type. This characteristic is needed in the trial and error classical solution and huge number of times. The new method is elaborated to overcome the laborious trial and error method. Here, the computation of the water surface angle becomes easy, simple, and direct.

The modified guided boring method (MGBM) is a new pipe installation method used in hard ground, where a conventional guided boring method is not applicable. Estimation of the required jacking force for pipe installation is critical for the design of MGBM projects; however, no such study has previously been performed. Hence, this paper presents a study on the jacking force estimation of pipe installation using MGBM. First, the field data of jacking force during the pipe installation stage of an MGBM project in Edmonton, Canada, was collected and analyzed. Second, three commonly used jacking force estimation models developed for microtunneling or pipe jacking installation were adapted to calculate the jacking force for this MGBM project, and the results were compared with the field data. The comparison indicated that an adapted model overestimated the field data. When the passive earth pressure was used as the face pressure, another adapted model yielded a close estimation to the field data, and a third model slightly underestimated the field data.

The main objective of the investigation was to evaluate the influence of the installation of two kinds of epoxy cured-in-place pipe (CIPP) liners (adhesive and independent) on the change in load capacity of concrete and vitrified clay pipes, and ring stiffness of polyvinyl chloride pipes. Adhesive liners stick to internal surfaces of the pipes, whereas independent liners do not stick to those. Load capacity and ring stiffness tests were carried out on samples made of pipes without liners (control samples) and those with liners. Pipe surface roughness was measured for control samples. Pull-off tests were performed on samples with adhesive liners. Mean liner thickness was determined for every sample with a liner. Results of the investigation show that change in load capacity or ring stiffness of the pipes with liners is positively correlated with adhesion strength between the pipe and the liner. Adhesion strength depends on the pipe internal surface roughness. The same load capacity or ring stiffness increase of the sewer pipes may be obtained by the installation of thinner adhesive or thicker independent liner. The results made it possible to determine adhesive liner thickness reducing coefficients.

A computing program has recently been developed to predict corrosion fatigue crack growth in pipeline steel in near-neutral pH environments. Supervisory control and data acquisition (SCADA) data are used as inputs for crack growth computation. The accuracy of crack growth prediction depends largely on whether the SCADA data have captured all the crack growth–contributing events of pressure fluctuations during the pipeline operation. In this work, statistical analyses of pressure fluctuations during oil and gas pipeline operation were performed to extract those pressure fluctuation parameters that affect corrosion fatigue crack growth in pipeline steel in near-neutral pH environments. High-resolution pressure data, which were recorded either with a very small sampling interval or at the time points whenever a measurable change in pressure was detected, were also modified to generate pressure spectra with different sampling intervals. The pressure points in the spectra could be the actual value of pressure at the time of recording (Method I) or an average value of all the pressure points within a given sampling interval (Method II). It was found that SCADA data generated by choosing large sampling intervals can miss both underload and minor load cycles and yield very conservative predictions, especially for oil pipelines. The SCADA data recorded by averaging pressure points within a given sampling interval (Method II) attenuate the amplitude of pressure fluctuations and yield more conservative predictions than those recorded by Method I. It is recommended that the data of pressure fluctuations during oil pipeline operation be recorded whenever a measurable pressure change has occurred in order to achieve more accurate predictions. In contrast, consistent predictions can be obtained when the pressure data of gas pipelines are recorded at a fixed sampling interval up to 20 min.

Offshore pipelines are commonly buried in seabeds for protection against damage, for better insulation, and to prevent upheaval buckling induced by thermal and pressure loadings. The seabed imperfection is one of the important design parameters determining the burial depth in order to achieve the required uplift resistance for a given pipeline. In this paper, the effect of variability in seabed profile on the performance of upheaval behavior of buried offshore pipeline is investigated. The variation in the seabed profile is modeled using random field theory. The field-observed imperfection height and correlation length are used to draw the samples of seabed profile for Monte Carlo simulation (MCS) using optimized Latin hypercube (LHC) sampling technique. In order to assess the safety requirement, a numerical model of a pipeline-seabed system was developed in a commercial finite element software ABAQUS assuming linear elastic behavior for the pipe material. The interaction between pipe and seabed soil was modeled using pipe-soil interaction elements in ABAQUS. The effect of irregular seabed on the performance of offshore pipeline against upheaval buckling was quantified on the basis of the probability of failure calculated using the simulation results. Analysis results showed that the irregular seabed profile can significantly increase the vulnerability of the pipeline (failure probability) during upheaval buckling. Results further revealed that the reliable distribution of seabed feature heights and lengths using surveys of out-of-straightness is required even from the front-end engineering design (FEED) phase to eliminate the unexpected pipe failure.

This paper offers an overview of available methodologies and provisions for the structural analysis and mechanical design of buried welded steel water pipelines subjected to earthquake action. Both transient (wave-shaking) and permanent ground actions (from tectonic faults, soil subsidence, landslides, and liquefaction-induced lateral spreading) are considered. In the first part of the paper, following a brief presentation of seismic hazards, modeling of the interacting pipeline–soil system is discussed in terms of either simple analytical models or more rigorous finite elements, pinpointing their main features. The second part of the paper outlines pipeline resistance, with emphasis on the corresponding limit states. Possible mitigation measures for reducing seismic effects are presented, and the possibility of employing gasketed joints in seismic areas is discussed. Finally, the discussed analysis methodologies and design provisions are applied in a design example of a buried steel water pipeline located in an area with severe seismic action.

In this study, the optimal design of a pipe network is proposed using a simulation–optimization model. Simulation and optimization were performed using the finite-element method (FEM) coupled with particle-swarm optimization (PSO). A finite-element–based simulation was applied to solve two benchmark problems: two-loop and Hanoi networks. The FEM-simulated results were compared with results from a software model, which revealed good agreement between these results. In addition, the developed FEM–PSO model was applied to design a real-life large pipe network. The results revealed a faster convergence of the proposed FEM–PSO model for designing pipe networks. The present study shows that the FEM can be used as an alternative simulation method in pipe network analysis and can also be easily coupled with search-based optimization techniques such as PSO.

This paper proposes a new method for hydrokinetic pressure and fluidic drag evaluation of non-Newtonian power-law slurries flowing within a borehole during horizontal directional drilling (HDD) pipe installation operations. The method divides the bore path into three segments, each associated with a different stage of slurry flow pattern. For each stage, assuming the product pipe and drill rod to be placed concentrically within the borehole, a set of coupled equations governing slurry flow within the borehole is derived. Then, to obtain the hydrokinetic pressure and fluidic drag history, the equations are solved at the desired product pipe leading head locations within a given segment. For two actual HDD installations completed in Alberta, Canada, the pullback forces have been collected and are compared against those estimated by the new proposed method and Pipeline Research Council International (PRCI) method. It is demonstrated that the new method can more accurately estimate the pullback forces.

Excavator-mounted hydraulic plate compactors are widely used in utility trench backfill compaction due to their efficiency. However, there are industry concerns about the possibility of pipe damage due to the combination of static downward earth pressure exerted by the excavator arm and dynamic earth pressure induced by the excavator-mounted hydraulic plate compactor. This paper presents the results of a field study that aims to compare the performances of utility trench compaction using a conventional walk-behind vibratory plate compactor with a lift thickness of 200 mm (8 in.) and an excavator-mounted hydraulic plate compactor with a lift thickness of 200 mm (8 in.), 300 mm (12 in.), 450 mm (18 in.), and 600 mm (24 in.). Three types of pipes are used. The field test results indicate that the excavator-mounted hydraulic plate compactor delivers compacted dry mass densities with a lift thickness of 200 and 300 mm comparable to the walk-behind vibratory plate compactor with a lift thickness of 200 mm; however, the excavator-mounted hydraulic plate compactor is not able to consistently achieve adequate compacted dry mass densities with a lift thickness of 450 and 600 mm. The excavator-mounted hydraulic plate compactor induces larger dynamic vertical earth pressures than does the walk-behind vibratory plate compactor. The excavator-mounted hydraulic plate compactor does not induce pipe damages in this study because the maximum strains in all pipes are smaller than 0.3%.

Leak detection is an essential topic within the policies of water loss management in drinking-water supply networks. This paper reports the results of an experimental campaign performed for assessing the sensitivity to water leaks of measurements of different vibroacoustic phenomena. The study represents the first stage of research aimed at developing a device for automatic leak detection in service pipes of water distribution networks. Leaks were artificially induced on a plastic pipe (length of 28 m and diameter of 32 mm) of a buried experimental facility. Vibroacoustic phenomena related to the leaking flow were monitored using a hydrophone and two accelerometers. A satisfactory leak-detection performance was achieved by processing the signals from both kinds of transducers.

Circumferential cracking or ring fracture has been identified as the most common type of failure mode for cast-iron water mains. However, the cause of circumferential cracking in water mains is not well understood. A number of different postulates exist in the literature on the causes of longitudinal stresses leading to circumferential cracking. The postulates are, however, not proven. This paper presents a finite element analysis to investigate the effect of corrosion pits on the failure mechanism of cast-iron water mains. The study shows that corrosion pits, voids in the bedding, and high relative stiffness of the pipe (with respect to the surrounding soil) can contribute to longitudinal stress development in the pipe wall. Longitudinal stress is generally higher than circumferential stress for a pipe with high relative stiffness. For a particular pipe, longitudinal stress is higher for smaller corrosion pits. Localized forces on the pipe wall from the surrounding ground can increase the longitudinal stress significantly. A localized support equivalent to a spring with a spring constant of $400\mathrm{N}/\mathrm{mm}$ can result in circumferential cracking of pipes. Based on the findings, a failure hypothesis has been provided for cast-iron water mains.

This paper investigates the redesigning of existing steel piping hydraulic systems to control severe water hammer positive and negative surges. The applied control strategy is based on adding a branched polymeric short penstock at the transient sensitive regions of the existing system. Two types of polymeric materials used for the short penstock, high-density and low-density polyethylene (HDPE and LDPE), are investigated. The one-dimensional unconventional water-hammer model, based on the Vitkovsky and the Kelvin-Voigt formulations, is used for hydraulic transient analysis, along with the fixed-grid method of characteristics implemented for numerical computations. The numerical model is validated using comparison with experimental measurements available in the literature. The results demonstrate that such a strategy can significantly mitigate the pressure increase and decrease induced by water hammer waves. Moreover, it is found that the short penstock volume and material represent the key factors affecting the damping rate of the positive and negative pressure peaks. The branching strategy used herein induces a smaller increase of the period than does the inline strategy and produces a similar pressure-head damping.

Culverts have been used to transmit surface drainage under roadways in place of typical short-span bridges because they provide an economical construction system. In this paper, a numerical study using a finite-element method is presented to study the behavior of reinforced concrete box culverts (CBC) with different dimensions and thicknesses under different soil fill heights. Four box-culvert sections were selected with width-to-height ratios of $2:1$, $1:1$, $2:3$, and $1:2$. Each section has a constant clear hydraulic area of $6.7\times {10}^6{\mathrm{mm}}^2$. Different thicknesses of CBC were investigated for each section. Hyperbolic stress-strain parameters for nonlinear finite-element analysis in soil masses were used. The required area of steel and deflection of culvert were calculated from each finite-element run. It is concluded that the CBC with a width-to-height ratio of $2:1$ is suitable for all soil fill heights examined (4.6, 9.1, 13.7, and 18.3 m). Finally, the paper presents a simple linear regression formula to predict section thickness for any soil fill height when using CBC-1.

Research has shown that polyolefin-based macrofibers can meet the requirements of the standards to consider their postcracking contribution in the structural design of fiber-reinforced concrete. The main drawback of such material is the lack of experience and the dependence on a suitable fiber distribution along the pieces. In this study, a real application of polyolefin fiber–reinforced concrete is reported. Its use enabled a reduction of the overall material cost and a total substitution of the customary steel-bar reinforcement. Moreover, it allowed an improvement in the concrete pouring rate and completion deadlines along the pipeline. In order to assure that structural requirements were fulfilled with reliability, quality control was a key point in the construction works, and therefore is also described. The conclusions revealed a noteworthy reliable performance of the polyolefin fiber–reinforced concrete, with there being a remarkably limited scatter of the residual strengths and provision of trustworthiness for its use in possible future structural applications.

The needs associated with the deteriorating water infrastructure are immense and have been estimated at more than $1 trillion over the next 20 years for water and wastewater utilities. To meet this growing need, utilities require the use of innovative technologies and procedures for managing their systems. The U.S. Environmental Protection Agency (USEPA) developed a demonstration program for pipe rehabilitation methods to help fill this gap. The program’s objective is to evaluate pipe rehabilitation technologies that can increase the effectiveness of the operation, maintenance, and renewal of pipelines. This paper provides an impartial assessment of the effectiveness and cost of four innovative technologies for water distribution and wastewater collection pipes. The technologies demonstrated include spray-on polymeric lining and cured-in-place pipe (CIPP) lining for water mains; and spray applied geopolymer mortar and an internal pipe sealing system for wastewater mains.

Vent pipes of natural gas compression stations can achieve very low temperatures during depressurization operations, and for such a reason their construction material is often specified to have a very low minimum design temperature. However, the pipe supporting structure can have higher design temperature specifications. During the depressurization operation, the vent pipe saddles are subject to a transient thermal evolution reflecting the vent pipe material cooling, governed by combined transient conduction and convection; however, the cooling of the supporting structure is less severe than that of the vent pipe, because of thermal inertia and ambient air mitigation. A transient heat transfer simulation scheme of typical saddle base supports, assimilated to rectangular fins, has been developed by modifying reference models and adopting a finite difference calculation approach. The new model has been validated in reference simulation scenarios, and it has been applied to typical pipe vent and associated supports configurations. The model allows one to determine the thermal interaction between pipes and supports and to assist in decision-making procedures for the engineering of the overall structure, as for instance the possible installation of thermal insulation if the cooling transmitted to pipe racks is excessive.

The exploitation of ultradeepwater fields often implies the use of large-diameter export pipelines. The installation of such large-diameter and long-distance export pipelines is commonly accomplished by applying J and S lay technology. In the case of complex and large fields, early export pipelines include inline valves on T/Y branches, with the relevant protection or foundation structures. When the resulting huge and heavy bulky items are to be carefully transferred from the firing line (FL) through the stinger to the touchdown point in the depths, a step out beyond the normal pipe lay is required. It involves the real-time control of operational parameters with a strict link to weather bulletins. This resolution is principally bound to the endorsement of the overall structural integrity of the as-laid pipeline and inline assembly while meeting the stringent installation tolerances (location, verticality, etc.) imposed by the circumstances. The use of large inline assemblies may cause additional challenges to the lay equipment, which is significantly impacted by heavy weight and geometrical or stiffness discontinuities. Nevertheless, for their installation, the occurrence and persistence of mild weather conditions at the right times during the lay campaign are of major concern. The limit sea states defined at the design stage for the pipe-lay dynamic allowance from encountered environmental load effects, superimposed on the static setting, may not be enough during operations. It is sometimes necessary to quantify the accumulated fatigue damage in real time immediately after the sea states are encountered and to anticipate the expected accumulation of fatigue damage in the next few days. This is needed because of the long-lasting deployment of the assembly onto the seabed. The rational and extensive use of weather forecasts, real-time monitoring, and numerical modeling of the structural response in smart combinations is a must. In this paper, a new engineering tool for the real-time prediction of the accumulated fatigue damage, based on actual sea states encountered during operation, is described.

This paper presents an explicit solution for the specific flow depths in partially filled pipes of circular cross-sectional area. Four depths encounter in most classical free-surface flow problems, namely the normal depth, the critical depth, the sequent depths from the specific momentum equation, and the alternate depths from the specific energy equation. This paper proposes new equations derived from dimensional analysis and gene expression programming to estimate directly those flow depths. The equations are examined over a wide range of flow and geometric conditions, providing satisfactory predictions when compared with the exact solution obtained from the governing hydraulic equations. Maximum error encountered in the critical and normal flow depths predictions is less than 1.25%, and maximum error encountered in the alternate and sequent flow depths predictions is less than 3.85%, which are acceptable in most hydraulic engineering practice. The equations are simple and would be useful in hydraulic engineering practice when quick and accurate estimates are needed of those depths, and can also be used to find the initial values for the flow depth in various theoretical and numerical schemes.

Laboratory experiments were carried out to investigate pressure drop in excess flow safety valves (EFSVs) assuming isothermal, incompressible, and one-dimensional gas flow. A particular focus was on Reynolds number effects. The analyzed quantities included gas pressure at the EFSV inlet and outlet cross sections, gas flow rate, and gas temperature, as well as open cross-section area of the EFSV. The experiments were performed for various Reynolds numbers, gas inlet pressures, and open cross-section areas of the EFSV. The results indicated some important findings. In particular, the pressure drop coefficient decreased as the Reynolds number increased. This was particularly exhibited for low Reynolds numbers characterizing laminar flow, while the pressure drop coefficient remained nearly constant in the turbulent flow. The pressure drop coefficient for the approximately equal Reynolds number was larger for smaller EFSV openings. The mathematical expressions linking the Reynolds number, pressure drop coefficient, and EFSV opening were provided to enable application of the reported results to pipeline designers.